Fluid-based switches such as liquid metal micro switches (LIMMS) comprise first and second mated substrates that define therebetween a number of cavities. Deposited within one or more of the cavities are a plurality of wettable surfaces that may be connected and disconnected by applying forces to a switching fluid. In some cases, the wettable surfaces may comprise electrodes, and the switching fluid may electrically connect and disconnect the electrodes to thereby control the propagation of electrical signals through the switch. In other cases, the switching fluid may connect and disconnect the wettable surfaces to block and unblock a plurality of windows in the cavities, thereby controlling the propagation of optical signals through the switch.